This invention relates in general to hatch cover cranes and, in particular, to a hatch cover crane having a hydraulically actuated jack to facilitate a hatch cover carried by the hatch cover crane being easily realigned over a cargo hold opening, as necessary.
More specifically, but without restriction to the particular use which is shown and described, this invention relates to a hatch cover crane having a hydraulically actuated jack wherein the jack is actuated to lift one end of the hatch cover crane off its support track to facilitate realigning the hatch cover carried by the hatch cover crane with the cargo hold opening, as necessary.
Generally, in cargo carrying ships, there are spaced openings along the top of the deck which are called cargo hold openings, or hatches. Various types of bulk materials are conveyed through these hatches into the ship's hold for transport across the sea.
In order to protect the cargo contained within the ship's hold from the adverse elements of the weather encountered during a voyage, there is a need for a closely-fitted covering over these hatches or openings, commonly called hatch covers. To provide adequate protection for the cargo, as well as to protect the safety of the ship during inclement weather, these hatch covers are made of a strong, heavy and durable metal. The use of such a heavy metal renders the hatch cover extremely bulky and causes difficulty in removing the hatch cover from the cargo hold opening. Due to their excessive weight and bulk, it is dangerous and inefficient to employ deckhands to manually remove or replace these covers.
Therefore, in order to safely and conveniently remove these hatch covers a hatch cover crane is used. In operation, the hatch cover crane is positioned directly over the hatch covers to provide an easy, efficient, and safe way to remove the hatch cover from the cargo hold opening. Since ships normally have a number of cargo hold openings in their deck, the hatch cover crane must be easily movable along the deck of the ship in order to be positionable over each hatch cover. For example, the hatch cover crane can be supported upon tracks or rails which are positioned on opposite sides of the hatches and extend a sufficient length to enable the crane to be positioned over each one of the cargo hatches.
An operator stationed upon the hatch cover crane itself can operate the crane to safely and efficiently remove the hatch covers. The operator positions the hatch cover crane directly over the hatch cover and a pair of hatch engaging hooks are lowered downward beneath the hatch crane. The hatch cover crane is then driven until the lowered hooks engage eyelets on the hatch cover. When the hooks engage the eyelets, the hooks are retracted thereby lifting the cover. In order to safely secure the hatch cover when in its raised position, surrounding each hook there is a rectangular hatch cover stop, laterally positioned to prevent the hatch cover from any oscillatory movement. The hatch cover stop is a safety device that secures the hatch cover to the hatch cover crane and prevents movement of the hatch cover caused by wind or wave motion of the water.
Due to the fact that the hatch cover crane may become out of alignment after running for a period of time, misalignment between the hatch cover crane and the cargo hold openings will occur. Thus, as the hatch cover crane, which is carrying the hatch cover, rolls along the tracks and is positioned over a cargo hold, the hatch cover may not be correctly aligned with the cargo hold opening.
In order to replace the hatch cover upon the cargo hold opening, it is important that the alignment between the hatch cover carried by the hatch cover crane and the cargo hold opening remain quite close due to the close fit of the hatch cover on the hatch opening. Cover alignment and fit with the cargo hold opening are very important both to protect the cargo and to maintain the seaworthiness of the ship. While every effort is made to maintain the alignment of the hatch cover carried by the hatch cover crane with the cargo hold openings, for the reasons previously discussed it is difficult to maintain.
The hatch cover crane described herein includes a hydraulic jack on one side of the hatch cover crane, and mounted between the crane wheelbase just above one of the support tracks or rails which extend substantially the length of the ship. The jack elevates one end of the crane above the track to allow the operator to drive the opposite end of the hatch cover crane forward or backward to align the hatch cover carried by the hatch cover crane with the hatch or cargo hold opening thereby effecting parallelism with the cargo hold openings.